The present invention relates generally to a dorsiflexion angle of a surgical patient's foot, and more specifically to a method and apparatus for determining a dorsiflexion angle of a surgical patient's foot during tendon surgery.
Cerebral palsy is a debilitating disease that affects many people. A common orthopedic problem in people with cerebral palsy is an equinus deformity, wherein the gastronemius and soleus muscles of the lower leg are permanently contracted. An equinus deformity may be surgically corrected if a tip-toe or toe-heel gait persists. Heel cord lengthening (HCL) surgery, in which the Achilles tendon is lengthened, is often used to correct equinus deformities. During the HCL surgery, a patient's foot is forcibly dorsiflexed (i.e., bending of the foot towards the shin) until the surgeon, based on his or her experience, subjectively determines the patient's foot is at a suitable maximum dorsiflexion angle with respect to the patient's corresponding leg. However, if the maximum dorsiflexion angle selected by the surgeon is too small, the patient's Achilles tendon will be under-stretched and the surgery may need to be repeated thereby increasing risk of complications to the patient. Additionally, if the maximum dorsiflexion angle selected by the surgeon is too high, the patient's Achilles tendon will be over stretched and the patient may have irreversible impaired function caused by an inability to produce adequate plantarflexion (i.e., bending of the foot away from the shin) torque during gait.